Furnace viewing window



FIG. 1 is a front perspective view of a furnace viewing window showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top side view thereof; and,

FIG. 7 is a bottom side view thereof.

The broken line shown in the drawings are for the purpose of illustrating portions of the article and form no part of the claimed design. 

CLAIM The ornamental design for a furnace viewing window, as shown and described. 